Well, english is not my first language, so i might be wrong. It is a linguistic argument, really.

But is it not why we use different words? Is it not to communicate different meanings?

Who's a thief?

Well, Someone (a 'thief') who, without catching attention, while you are at work, without making much noise, walks (or even breaks) into your house, takes something and leaves. 'Steals' it.

Or a pickpocketer is a kind of thief. someone who silently, without your knowing, slips something out of your pocket.

I argue that someone who stops you on the street, shows you their holstered gun and asks for your watch isn't.

In a store, when Mr. Greygloves silently puts something in their pocket and walks out without paying, he commits a 'theft'. More accurately, a shoplifter.

If Mr. Greygloves was to talk to the cashier and THREATEN him with violence if he (the cashier) does not give him the cash,

would that not be a robbery?

Mr. Cooper boards on a plane and silently slips the in-flight magazine into his suitcase. That's a theft.

If Mr. Cooper was to board on a plane and silently hand a piece of paper to the attendant

"miss, i have a bomb in my briefcase. I demand USD200,000",

would Mr. Cooper not be a robber of century? No immidiate violence. Just the threat of it.

Another example:

Man in a suit, early 30s, fit, approaches your shop's manager and, with italian accent, politely - without immidiate violence - asks that you pay the 'racket'. You could imagine - or you heard from your fellow workers - how many bones were left intact on the last guy who answered "no". If you give him the money, is that really just theft?

Yet, when that guy has an IRS badge on his suit, it suddenly is (a theft and not robbery) ?